First principles simulations of fluid water: The radial distribution functions

Abstract

We apply a recently developed first principles but simplified molecular dynamics method to the simulation of water at different conditions. The computational simplicity of this method allows its application to systems containing a significant number of molecules, yet still taking explicitly into account the quantum electronic structure of the system. In the present work we simulate a system of 216 H2O molecules with periodic boundary conditions at two different densities (ρ = 1.0 g/cm3 and ρ = 0.72 g/cm3 and temperatures ranging from ∼300 K to ∼580 K. The effect of density and temperature on the structure of water is analyzed by means of the partial radial distribution functions gOO, gOH and gHH. We find an important reduction of the hydrogen-bond peak for water at the supercritical conditions ρ = 0.72 g/cm3, T = 580 K, in good agreement with recent experimental results. © 1997 American Institute of Physics.